The increasing requirements of container transportation in the world and the continuous increment of the handling capacity of the container port put forward new and increased demands on the technical equipment for loading and unloading containers, and an urgent need for the design and development of high efficient bank-run container load and unload systems to meet the demand of the lifter productivity needed by the larger ships.
The main lifting machinery of the crane of the prior art carries out the lifting and lowering operation of one hanger tool only, hence only one 40 feet container or two 20 feet containers can be lifted at a time so that limits the production efficiency and does not meet the market requirement.